The present disclosure relates to a control device whose control target is a vehicle drive device that is provided with a transmission mechanism and a rotating member in a power transmission path in this order from a drive power source side, the power transmission path connecting the drive power source to wheels, and that is provided with a parking lock mechanism that restricts rotation of the rotating member by allowing an engaging member to engage with the rotating member.
For a control device such as that described above, a control device described in JP 2002-295657 A is known. As described in JP 2002-295657 A, a parking lock mechanism [parking mechanism 1] is controlled by a control device [control unit 100] such that when a parking range that locks wheels is selected by a range selection device [shift lever 40] provided in a vehicle, the parking lock mechanism goes into a locked state in which an engaging member [parking pawl 3] engages with a rotating member [parking gear 2], and when a drive range that allows the vehicle to travel forward or backward is selected by the range selection device, the parking lock mechanism goes into an unlocked state in which the engagement of the engaging member with the rotating member is released.
The control device described in JP 2002-295657 A is configured such that when the drive range is selected by the range selection device with the parking lock mechanism being in the locked state and the vehicle stopped on a hill, before the parking lock mechanism is switched to the unlocked state, a forward drive range is formed if the hill is an uphill slope and a reverse drive range is formed if the hill is a downhill slope. Namely, the control device is configured such that a drive range is formed such that counter torque which is torque in a direction in which load imposed by the self-weight of the vehicle is cancelled out acts on the rotating member on which the load is acting, from the drive power source side, and in this state the parking lock mechanism is switched to the unlocked state. By this, comparing to a case in which the parking lock mechanism is switched to the unlocked state before forming a drive range, the magnitude of a load accumulated in the rotating member at a point in time when the parking lock mechanism is switched to the unlocked state can be reduced, enabling to reduce shock that can occur upon switching the parking lock mechanism to the unlocked state.
Meanwhile, when control such as that described above is performed, a situation can occur in which a vehicle driver steps on an accelerator pedal during a period before the parking lock mechanism is switched to the unlocked state. When such a situation occurs, depending on the amount of stepping on the accelerator pedal, the magnitude of the counter torque becomes excessive over the load imposed by the self-weight of the vehicle, which can cause a state in which a relatively large load in an opposite direction to the load imposed by the self-weight of the vehicle is accumulated in the rotating member. If the parking lock mechanism is switched to the unlocked state in such a state, then relatively large shock can occur. However, JP 2002-295657 A does not describe this matter.